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05 May 2021

Nature vs. machine and the quest to capture carbon

Luke Baker

Global governments are starting to pick up the pace around climate change. Whether it’s Biden’s pledge to reduce U.S. emissions by 50% by 2030 or Boris’ to reduce the U.K’s by 78% by 2035, there is a lot of work to do.

But as you start to uncover what this will actually take you can see there are some sectors that are going to be really tricky to decarbonise. Whether that is airlines where the laws of physics make battery-powered planes just unfeasible or the production of a whole range of materials from concrete and steel to glass and fertiliser.

We however do have the ability to not just emit CO2 into the atmosphere but also take it in and store it in various forms. This is of course nothing new; there are a number of natural processes that have been doing this for millennia.

Let’s do a quick rewind to Secondary School Geography and remind us of where all this carbon currently sits. Starting with the atmosphere where we need to pull this CO2e out from. Since 1850 humans have emitted about 2,400 gigatonnes of CO2e (a gigatonne is 1,000,000,000 tonnes). Around 950 gigatonnes of that CO2e went into the atmosphere with the oceans and land absorbing the remaining 1,450 gigatonnes of CO2e.

As a result, our atmosphere today has 419.40 parts of CO2e per million (it was around 360 parts per million in 1960). This is important because global governments agreed to limit this to around 450 parts per million to keep temperature rises well below 2 degrees centigrade.

The question is can we ramp up these planetary processes of the oceans and land to pull in more CO2e from the atmosphere or do we need to look to technology to accelerate it?

The Tree

Let’s start by looking on land and one of the literal giants of carbon capture; the tree. Back in 2019 a bit of a stir was created with a study from the Crowther Institute led by British academic Thomas Crowther. It showed the world could support an additional 0.9 billion hectares of forest representing a 25% increase in forested area. This would hold more than 200 gigatonnes of additional carbon at maturity. That’s a whopping 25% of the current atmospheric carbon pool.

And there are a lot of organisations focusing on scaling up tree planting, particularly as a means for businesses to offset their emissions. Technology is increasingly being utilised also to help lower the cost to plant trees with the use of drones and on land technology from the likes of Dendra and the Land Life Company.

We’re also seeing a range of companies utilising satellite imagery to monitor existing tree stocks such as Sylvera and Pachama. This not only is being used to monitor the tree cover but also estimate the carbon stock within that tree cover.

And the soil beneath

The story doesn’t end here though; part of the carbon sequestered is actually in the soil it sits. In fact, it’s estimated that the total soil on earth holds around 1,500 gigatonnes of carbon.   

This can be massively increased also, due to poor farming practices carbon levels in soil has decreased dramatically over the past century. In fact, a study estimated that carbon levels in Australian soils may have historically been double the current 1.6 to 4.6 per cent range before intensive agriculture took hold. As a result, there are companies now looking at rewarding farmers that look after the long-term health and organic carbon within soils through carbon credits. One such company is Regen Network whose platform validates this entire process. 

The Oceans

One of the largest carbon stores is the ocean, holding around 38,000 gigatonnes of carbon. And scientists have recently been exploring a potential way to ramp up this process. One of the most promising is Project Vesta who are exploring a natural process that’s happened for millions of years on the shores of oceans. The process takes a substance called olivine found at volcanic sites naturally and places it on beaches, when the substance reacts with the ocean and wave energy it pulls in CO2, reduces ocean acidity and locks up the CO2 in limestone at the bottom of the ocean.

We’re also seeing companies developing vegetation in the ocean as a carbon store. The U.K. based Sea Grown utilises seaweed as not only a great food source but also to means of capturing carbon. Seaweed is a very underutilised food source particularly in the western world and it can sequester up to 20 times more carbon per acre than land forests.

Can and should we mimic nature?

With all these powerful natural processes in place that we can accelerate it begs the question as to why we’d look to do the job of nature at all? In the world of carbon capture, there are companies working on capturing carbon in three areas.

First of all within heavy industry, here carbon capture is taking place at the main source of some of the biggest emitters preventing it from reaching our atmosphere. They convert the emissions at source into a liquid form of carbon and then inject it back down deep into the earth.

Today according to the Global CCS there are 66 such carbon capture and storage facilities across the globe. There is a high concentration of them in the U.S. due to a tax legislation called 45Q. It gives companies the ability to reduce down their tax bill by $50 per tonne of carbon captured and stored. The other big plus for the U.S. is that they have an estimated 205 billion tonnes of underground storage to utilise.

We’re also seeing companies building out these capabilities in the EU due to the emissions trading system (ETS) where the cost of emitting a tonne of CO2 just hit EUR50.

Whilst these heavy emitters such as oil and gas, concrete and steel may need to move aside as we innovate away the need for them at all, this could provide a way of reducing down emissions in the short term to buy us more time.

The second way in which carbon capture is being attempted is through direct air capture (DAC). This is more tricky because as we know there are not so many CO2 parts per million in the air. There are however companies such as Carbon Engineering in Canada and Climeworks from Switzerland who are attempting to do exactly this. Climeworks takes the CO2 from the atmosphere using giant fan systems and buries it underground as stone. They’re attracting funding from the likes of Stripe who are using it to offset their emissions. The cost per tonne of CO2 still remains high at around £880 per tonne. If however, they can get the price down as they scale it offers a very interesting opportunity to capture carbon with a very low area of land used.

Finally, there are organisations that are not only looking to take CO2 from the air but also make useful things out of it. Whether that is food proteins from U.S. firm Air Protein or diamonds from U.K. firm; Sky Diamonds. Whilst not at the scale of CCS, these new ways to actually utilise CO2 offer an exciting sustainable vision for the future.

One thing is for sure, we are now seeing a momentum shift in the space. Whether that be the business world funding projects for offsets or companies looking to use technology and insights to accelerate carbon capture through natural or man-made processes. And if we are to have a chance of staying within 2 degrees we’re going to need them all to move at pace alongside emissions reductions over the coming decade.

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